VB.NET textbox remove last dash - vb.net

Question

How can I remove the last - added after the code has been entered.
All the - are automatically added.
Here my code :
Dim strKeyTextField As String = txtAntivirusCode.Text
Dim n As Integer = 5
Dim intlength As Integer = txtAntivirusCode.TextLength
While intlength > 4
If txtAntivirusCode.Text.Length = 5 Then
strKeyTextField = strKeyTextField.Insert(5, "-")
End If
Dim singleChar As Char
singleChar = strKeyTextField.Chars(n)
While (n + 5) < intlength
If singleChar = "-" Then
n = n + 6
If n = intlength Then
strKeyTextField = strKeyTextField.Insert(n, "-")
End If
End If
End While
intlength = intlength - 5
End While
'' Define total variable with dashes
txtAntivirusCode.Text = strKeyTextField
'sets focus at the end of the string
txtAntivirusCode.Select(txtAntivirusCode.Text.Length, 0)
Output is : XXXXX-XXXXX-XXXXX-XXXXX-XXXXX-
What I want : XXXXX-XXXXX-XXXXX-XXXXX-XXXXX

Answer 1

You could just remove the last char in the string like that:
txtAntivirusCode.Text = strKeyTextField.Substring(0, strKeyTextField.Length - 1)
or
txtAntivirusCode.Text = strKeyTextField.Remove(strKeyTextField.Length - 1)
or
txtAntivirusCode.Text = strKeyTextField.Trim({" "c, "-"c})
or
txtAntivirusCode.Text = strKeyTextField.TrimEnd(CChar("-"))
If there is a possibility of a space at the end of the string use .Trim() before Substring and/or Remove

Answer 2

The other way from removing the last "-" is to not add the last "-", for example:
Dim s = "ABCDE-FGHIJKLMNOPQRSTUVWXYZ"
Dim batchSize = 5
Dim nBatches = 5
Dim nChars = nBatches * batchSize
' take out any dashes
s = s.Replace("-", "")
' make sure there are not too many characters
If s.Length > nChars Then
s = s.Substring(0, nChars)
End If
Dim sb As New Text.StringBuilder
For i = 1 To s.Length
sb.Append(s.Chars(i - 1))
If i Mod batchSize = 0 AndAlso i <> nChars Then
sb.Append("-")
End If
Next
Console.WriteLine(sb.ToString())
Console.ReadLine()
Outputs:
ABCDE-FGHIJ-KLMNO-PQRST-UVWXY